The present invention relates generally to thermographic monitoring of electrical equipment and, in particular, to electrical switchgear allowing improved thermographic monitoring.
Preventive and predictive maintenance techniques provide for the monitoring of equipment to avoid costly repair and lost production associated with unexpected equipment failures. Preventive maintenance institutes regularly scheduled monitoring of electrical, equipment, component replacement, and minor repairs. Predictive maintenance uses monitored data to more accurately assess maintenance scheduling and equipment replacement.
Thermographic monitoring employs cameras that are sensitive in the far infrared region (typically 3-15 μm) to provide non-contact thermal measurement of surface temperatures of equipment. Particularly for electronic equipment such thermographic images may provide advanced warning of equipment failure that would not otherwise be apparent. High temperatures may indicate, for example, high resistance electrical junctions, overvoltage or overcurrent, damaged insulation or damaged conductors that may ultimately lead to catastrophic failure. A thermographic image can be taken while the equipment is in operation with minimal operator risk. A thermographic image can encompass multiple equipment components allowing rapid monitoring of many potential failure points.
Electrical switchgear, such as contactors and the like, is typically encased in a housing of electrically insulating, fire retardant material intended to protect users from electrical arcing and high voltages, as well as to protect internal components of the switchgear from external contamination. The materials from which such housings are constructed must meet a demanding set of requirements including: high temperature resistance, high tensile strength, high flexural modulus, low warpage, good dimensional stability, and low moisture absorption. The need to encase the electrical components of the switchgear in such materials can limit the effectiveness of thermographic monitoring of switchgear, requiring substantial rise in the temperature of the housing before a thermographic image can be obtained.